Contact washer system and method for controlling a windscreen wiper motor

ABSTRACT

[The present invention relates to a] A contact-disk system is described having a rotatable contact disk [( 10 )] and a plurality of contact elements [( 12, 14, 16, 18 )], the contact disk [( 10 )] having a plurality of paths [( 20, 22 )] and each contact element [( 12, 14, 16, 18 ) is] being assigned to one path [( 20, 22 ), the contact disk ( 10 ) having two paths ( 20, 22 )]. Two selected contact elements [( 12, 14 )] of the plurality of contact elements [( 12, 14, 16, 18 )] are always at the same electrical potential and glide on the same path [( 20 ). The present invention also relates to a]. A windshield-wiper motor and a method for controlling a windshield-wiper motor are also described.

[0001] The present invention relates to a contact-disk system having a rotatable contact disk and a plurality of contact elements, the contact disk having a plurality of paths and each contact element being assigned to one path. The present invention also relates to a method for controlling a windshield-wiper motor using a contact-disk system having a rotatable contact disk and a plurality of contact elements, the contact disk having a plurality of paths and each contact element being assigned to one path. Furthermore, the present invention relates to a windshield-wiper motor which comprises a contact-disk system having a rotatable contact disk and a plurality of contact elements, the contact disk having a plurality of paths and each contact element being assigned to one path.

BACKGROUND INFORMATION

[0002] Windshield-wiper devices with the generic contact-disk systems as well as generic methods for controlling windshield-wiper motors are known especially for cleaning of motor vehicle windshields. The windshield-wiper devices are usually operated by a switch which is located in the vehicle interior, the switch generally being implemented as a steering-column switch. By operating the steering-column switch, the windshield-wiper device may be shifted from a switched-off state to at least one operating state. In most cases, the operating states are implemented by a plurality of windshield-wiper speeds and an intermittent control.

[0003] To ensure that the windshield wipers do not come to rest in an intermediate position when the windshield wiper is switched off by the steering column switch, but instead are properly guided back to park position, the use of contact-disk systems is known. Such contact-disk systems maintain a closed circuit, in which the windshield-wiper motor operates, until the windshield wipers have reached the park position.

[0004] FIG. 1 shows a contact disk 110 which is used in a contact-disk system according to the related art. A contact disk 110 of this kind is installed in generic windshield-wiper motors in such a way that it rotates in synchronism with the windshield-wiper motor. Contact disk 110 establishes contact with three contact elements, which in each case glide on one path of contact disk 110. A first contact element glides on outer path 120, which has a gap. A second contact element glides on inner path 122, which is implemented as a short path, and a third contact element glides on a center path 121, which is continuous. Such a construction makes it possible to maintain a current flow in all motor settings, except for the end position and in an area approaching the end position. This is achieved by a contact element, which is connected to the positive pole of the battery, gliding on outer path 120. A contact element gliding on center path 121 is connected to the wiper motor. Therefore, a current flow from the positive pole of the battery to the wiper motor is maintainable as long as the first contact element glides on a conductive region of outer path 120. The current flow will only be interrupted when contact disk 110 has rotated to the point where the contact element is located in the gap in outer path 120. Due to the inertia of the motor, the contact disk continues to rotate despite the interrupted current flow. However, this further rotation will come to an end when the conductive region of short, inner path 122 connects with a contact element. This contact element is switched such that the motor is short-circuited and is actively braked in this manner.

[0005] Due to the three paths of the contact disk according to the related art, it has a certain minimum size. However, in the case of windshield-wiper motors it is desirable to achieve an overall size that is as small as possible, and, therefore, in particular also a small size of the contact disk. A small size of the contact disk would also be advantageous in the production of windshield-wiper motors, in particular in rear-wiper motors with oscillating gears, where the contact disk must currently be arranged with the contacting on the opposite side with respect to the oscillating gear. For this reason, the windshield-wiper motor must at present be rotated on the assembly line during production, which makes the production process expensive.

SUMMARY OF THE INVENTION

[0006] The present invention builds on the generic contact-disk system in that the contact disk has two paths and in that two selected contact elements of the plurality of contact elements are always at the same electrical potential and glide on the same path. In this manner it is possible even with a two-path contact disk to maintain an electric current flow until the park position of the windshield wiper is reached or until shortly before the park position has been reached. Because the contact disk needs no more than two paths it has a smaller size and a smaller radial overall width, which has advantages with respect to the mentioned overall size of the windshield-wiper motor and in view of the manufacturing process.

[0007] Preferably, the selected contact elements glide on a first path, which has an electrically conductive and an electrically insulating area, and at least one contact element of the selected contact elements is connected to the electrically conductive area. If the windshield-wiper motor is switched off by operating the steering-column switch, an electrical connection to the wiper motor is being maintained at least via one of the selected contact elements, since at least one of the selected contact elements is always in contact with the electrically conductive area of the first path.

[0008] Preferably, the electrically insulating area of the first path is implemented by a gap in a conductive path, and the selected contact elements have a spacing that is larger than the gap of the first path. Therefore, given a circular contact disk, the electrically insulating area may be realized by a cut-out with radially extending boundaries. If the opening angle of this gap is less than the clearance angle of the selected contact elements, it is assured in this manner that one of the selected contact elements is always in contact with the electrically conductive area of the first path.

[0009] It is especially preferred if a first, additional contact element glides on the first path. This first additional contact element is used to maintain an electrical connection between the contact disk and the positive pole of the vehicle battery. Therefore, even when the steering-column switch is in the off-position, an electrical connection is maintained between the positive pole of the battery and the motor via the first additional contact element and at least one of the selected contact elements. Only when the first additional contact element leaves the electrically conductive area of the first path and is located in the insulating area of the first path, will the current flow be interrupted.

[0010] It is particularly advantageous if a second path has an electrically insulating area and an electrically conductive area and if a second additional contact element glides on the second path. This contact element is used to realize an electrical short-circuit of the motor and to actively brake the motor in this manner once the park position has been reached.

[0011] Preferably, the gap in the first path, the electrically conductive area of the second path, the first additional contact element and the second additional contact element are arranged with respect to one another in such a way that a state exists in which neither the first additional contact element nor the second additional contact element are connected to an electrically conductive area of the first path and the second path, respectively. Although the current flow in the electrical circuit of the windshield-wiper motor is already interrupted, the motor and the contact disk still continue to rotate, due to their inertia. During this phase the motor speed is being reduced, and an active braking of the motor only takes place, due to the electrical short-circuit, when the second additional contact element makes contact with the electrically conductive area of the second path.

[0012] It is particularly useful if the angular range, which is covered by the electrically conductive area of the second path, is less than the angular range that is covered by the electrically insulating area of the first path. As a result, it is possible that the first additional contact element has already left the conductive area of the first path due to the rotation of the contact disk, while the second additional contact element has not yet reached the conductive area of the second path. Therefore, the motor is neither actuated nor actively braked in this intermediate state. The motor continues to rotate due to its inertia, with the rotational speed decreasing, however. Only when the electrically conductive area of the second path makes contact with the second additional contact element, will the motor be finally braked.

[0013] Preferably, these contact elements are contact springs. In this manner, a reliable contact between the contact disk and the contact elements is established.

[0014] The present invention builds on the generic method in that a contact-disk system according to the present invention is used to control a windshield-wiper motor. In this manner, the advantages of the contact-disk system according to the present invention are implemented by a control method.

[0015] In the method according to the present invention it is particularly advantageous if a switch connected to the contact-disk system is operated and if a rotation of the contact disk is maintained until the second additional contact element is connected to the electrically conductive area of the second path. Thus, the control method advantageously allows to guide the windshield wipers from one operating position to a park position in a reliable manner.

[0016] In this context, it is particularly advantageous if, prior to connecting the second additional contact element to the electrically conductive area of the second path, the connection of the first additional contact element to the electrically conductive area of the first path is interrupted. Although the electrical connection of the motor and the battery is already interrupted during this thus created intermediate state, rotation still occurs nevertheless, due to the inertia of the involved components, although the rotational speed of the motor decreases. Only when the second additional contact element contacts the electrically conductive area of the second path does an active braking of the motor take place.

[0017] The present invention builds on the generic windshield-wiper motor in that it has a contact disk according to the present invention. As a result, the windshield-wiper motor implements the advantages of the contact disk according to the present invention and the method according to the present invention. It is particularly advantageous that a windshield-wiper motor may be manufactured that has a reduced size.

[0018] The present invention is based on the surprising recognition that, by an appropriate arrangement of contact elements and a suitable geometric design of a contact disk, it is possible to realize the functions of a three-path contact disk, as it is used in windshield-wiper motors of the related art, also by two-path contact disks. Therefore, windshield-wiper motors 

13. (New) A contact-disk system, comprising: a rotatable contact disk having a plurality of paths; and a plurality of contact elements, each contact element being assigned to one of the plurality of paths, wherein two selected contact elements of the plurality of contact elements are always at a same electrical potential and glide on a same path.
 14. (New) The contact-disk system according to claim 13, wherein there are two paths.
 15. (New) The contact-disk system according to claim 13, wherein: the plurality of paths include a first path having an electrically conductive area and an electrically insulating area; the two selected contact elements slide on the first path; and at least one contact element of the two selected contact elements is connected to the electrically conductive area of the first path.
 16. (New) The contact-disk system according to claim 15, wherein: the electrically insulating area is realized by a gap in the electrically conductive area; and a spacing between the two selected contact elements is larger than the gap in the electrically conductive area.
 17. (New) The contact-disk system according to claim 16, wherein the plurality of contact elements include a first additional contact element which glides on the first path.
 18. (New) The contact-disk system according to claim 17, wherein: the plurality of paths include a second path having an electrically insulating area and an electrically conductive area; and the plurality of contact elements include a second additional contact element which glides on the second path.
 19. (New) The contact-disk system according to claim 18, wherein the gap in the electrically conductive area of the first path, the electrically conductive area of the second path, the first additional contact element, and the second additional contact element are arranged so that the first additional contact element is not connected to the electrically conductive area of the first path and the second additional contact element is not connected to the electrically conductive area of the second path.
 20. (New) The contact-disk system according to claim 18, wherein an angular range covered by the electrically conductive area of the second path is less than an angular range covered by the electrically insulating area of the first path.
 21. (New) The contact-disk system according to claim 13, wherein the plurality of contact elements include contact springs.
 22. (New) A method for controlling a windshield-wiper motor using a contact-disk system, comprising: configuring a rotatable contact disk to have a plurality of paths including a first path having an electrically conductive area and an electrically insulating area and a second path having an electrically insulating area and an electrically conductive area; configuring a plurality of contact elements; assigning each contact element to one of the plurality of paths; arranging two contact elements to be at a same electrical potential and to glide on a same path; arranging the two selected contact elements to slide on the first path; connecting at least one contact element of the two selected contact elements to the electrically conductive area of the first path; configuring the electrically insulating area of the first path to be a gap in the electrically conductive area of the first path; arranging a space between the two selected contact elements to be larger than the gap; arranging a first additional contact element of the plurality of contact elements to glide on the first path; arranging a second additional contact element to glide on the first path; arranging the gap in the electrically conductive area of the first path, the electrically conductive area of the second path, the additional contact element, and the second additional contact element so that the first additional contact element is not connected the electrically conductive area of the first path and the second additional contact element is not connected to the electrically conductive area of the second path; and configuring an angular range covered by the electrically conductive area of the second path to be less than an angular range of the electrically insulating area of the first path.
 23. (New) The method according to claim 22, further comprising: operating a switch connected to the contact-disk system; and maintaining a rotation of the contact disk until the second additional contact element is connected to the electrically conductive area of the second path.
 24. (New) The method as recited in claim 22, further comprising: disconnecting the first additional contact element from the electrically conductive area of the first path prior to connecting the second additional contact element to the electrically conductive area of the second path.
 25. (New) A windshield-wiper motor, comprising: a contact-disk system including a rotatable contact disk having a plurality of paths and a plurality of contact elements, each contact element being assigned to one of the plurality of paths, wherein two selected contact elements of the plurality of contact elements are always at a same electrical potential and glide on a same path. 